1977

6.8

1985

6.2

1964

7.0

1984

6.2

1999

7.0

1985

6.7

2000

6.5

2006

6.9

2001

6.9

1988

7.8

2005

7.1

1994

6.2

1986

7.5

1946

7.7

1998

6.4

1995

7.3

1990

7.0

2007

6.1

1984

6.0

2003

6.8